Lomustine is a prescription chemotherapy agent used with other medicines in the treatment of CNS tumors, lymphomas, mast cell tumors, and sarcomas. Lomustine Compounded capsule is a blue and white elongated capsule made specifically for your pet. Wear gloves when handling and administering this medicine. Do not open or split this capsule. Lomustine can be found in a treated animal's secretions, including saliva, vomit, and feces. Wear gloves when changing the cat litter box, picking up waste, or cleaning up vomit.